1. Field of the Invention
This invention relates to electrostatic copier devices and more particularly to a toner residue cleaning device for cleaning the intermediate carrier of such copiers.
2. Prior Art
The present invention is directed to a cleaning device for use in cleaning intermediate carriers of the kind which are used in electrostatic printers or copiers. Such cleaning devices are used to remove toner residues left behind on the intermediate carrier after completion of the sequential functions of charged latent image formation, image toner development and toner image transfer to a recording carrier. Such devices may contain a brush which wipes the toner residue from the intermediate carrier into a shroud surrounding the brush which shroud may be connected to a suction device.
Such cleaning devices for removal of toner residues from intermediate carriers in electrostatic copiers or printers are known. See for example U.S. Pat. No. 2,832,977. In electrostatic copiers of this type latent charge images of the character or image to be printed are produced electrographically or electrophotographically on an intermediate carrier such as a drum which is provided with a dielectric or photoelectric layer or surface. The charge images are thereafter developed at a developing station by the application of toner to the surface in a pattern determined by the latent image. Subsequently the toner image is transferred at a transfer station to a recording carrier, such as a paper sheet or web. After transfer, however, some toner residue may still remain on the intermediate carrier. Such residues must be removed before the intermediate carrier passes back again to the charging station inasmuch as residues remaining on the intermediate carrier surface will adversely affect subsequent image formation and printing.
It is well known to remove toner residues from the intermediate carrier by means of a bristled brush which is positioned such that the bristles wipe along the intermediate carrier's surface. Toner residues adhering to the brush are thereafter removed from the brush with the aid of a suction device.
To facilitate suction removal, the brush may be surrounded by a cowl or shroud which is, in turn, connected to the suction device. Cleaning of the brush can be further enhanced by providing a doctor strip or doctor blade adjacent the brush which helps to strip toner residues from the brush.
Preferably the brush has a length which corresponds to the length of the data carrier, normally a drum. Therefore the shroud is at least as long as the brush and, in order to assure that all toner residues are withdrawn from the cowl, the airflow by the suction device must be sufficiently large throughout the shroud so that the airflow at any given point is sufficient to extract the toner residue. When utilizing electrostatic printers which are capable of handling large paper widths, the corresponding drum, brush and shroud are thus considerably enlarged thereby requiring a very high performance suction device.
It would therefore be an advance in the art to provide for adequate toner removal from the shroud without the necessity of providing a high performance suction device.